The term belongs to the “Amorite” system of kin designations and is attested mainly in Mari corpus; Akkadian proper employs analytical expressions to designate uncle and aunt, e.g. aḫi abim, aḫāt abim and so on.
wa-yaˁámer heʸh díˀʸheʰ dédoʰ tóˀo ˁö́ḳar ḥóuton ɛʰ di-dédoʰ ‘When he grew up, his uncle said to him: “You should be circumcised, my nephew!”’ (CSOL I 28:8)